1. Field of the Invention
The present invention relates to methods for evaluating filming occurrence on electrophotographic photoconductors (hereinafter sometimes referred to as “photoconductor”, “latent electrostatic bearing member”, or “image bearing member”), devices for evaluating electrophotographic photoconductors, and methods for reusing electrophotographic photoconductors. The “evaluation of filming occurrence” in the present invention encompasses the evaluations with respect to existence or nonexistence of filming, degree of filming, and quantification of filming.
2. Description of the Related Art
In electrophotographic image forming apparatuses, such problems as so-called “filming phenomena” are likely to occur, where paper powders, toner components, fine carrier particles etc. deposit or adhere on surfaces of electrophotographic photoconductors when images are formed repeatedly.
Here, the term “filming phenomena” refers entirely to such phenomena as (i) resins and/or wax ingredients in toners adhere to electrophotographic photoconductors, (ii) silica particles in toners bite into surfaces of electrophotographic photoconductors, (iii) titanium oxide particles in toners bite into surfaces of electrophotographic photoconductors, (iv) degraded substances such as of zinc stearate adhere to electrophotographic photoconductors, and (v) foreign matters including paper powders, carrier fine powders, dusts etc. adhere to electrophotographic photoconductors.
Such “filming phenomena” often appear along circumferential direction of electrophotographic photoconductors, and inferior images such as streaks, image deletion and black voids are likely to generate even the thickness of the filmings being as thin as approximately 0.1 μm, therefore, evaluation of the filming occurrence has been needed.
For instance, Japanese Patent (JP-B) No. 3368082 discloses judgment or evaluation of filming occurrence by visual observation of inspectors. However, there have been problems that initial filming occurrence or slight filmings are significantly difficult to find and the evaluations are often different between individual inspectors.
Japanese Patent Application Laid-Open (JP-A) No. 2004-086107 discloses detection of filming occurrence on the basis of current change of driving motors. However, the current change is negligible at initial filming occurrence or slight filmings, therefore it is considerably difficult to detect correctly the filming occurrence.
In addition, detection of filming occurrence or clearing of filmings is proposed on the basis of change of surface voltages at electrophotographic photoconductors (see JP-A Nos. 2000-242145, 2001-22225, 2000-147953, and 11-133830). However, these proposals are insufficient for detecting accurately the filming occurrence in cases of small change of surface voltages such as at initial filming occurrence or slight filmings. In addition, in cases of local filmings, there exists a problem that the filming cannot be detected unless the voltage-detecting part of devices coincides with the site of the filming.
JP-A No. 11-272137 discloses that another removal of filmings, when potential of photoconductors exceeds a pre-determined level, brings about accurate timing of the filming removal, which leading to prevent image deterioration and to provide stable images.
JP-A Nos. 2003-215982 and 10-91003 discloses optical detection of filming occurrence on electrophotographic photoconductors. However, electrophotographic photoconductors, in accordance with these proposals, suffer from a number of flaws due to scratch in use, which makes difficult to evaluate film occurrence because of the fluctuation of optical reflection conditions.
JP-A No. 07-55710 discloses a use of CCD cameras in which an optical reflection from photoconductor drums is introduced into the camera, flaws on the surface of the photoconductor drum, foreign matters mixed into photosensitive layers etc. are detected from the optical reflection. However, the difference between flaws and filmings are difficult to distinguish, since a number of flaws appear on the photoconductor surface due to scratch with the prolonged use.
As described above, it is difficult to evaluate and determine visually the filming occurrence in the prior art. Electrical or optical methods are also difficult to accurately determine the initial or slight filmings, as such, developments for evaluation methods are currently desired that can detect easily and accurately filmings even they are slight and/or partial.
On the other hand, electrophotographic photoconductors comprising a photosensitive layer on a support have been utilized widely for the electrophotographic photoconductors of electrophotographic image forming apparatuses such as copiers and printers. These electrophotographic photoconductors have also been utilized widely in process cartridges that further contain a developing device, cleaning device etc. within a case for easier exchangeability.
Recent years, various trials have been carried out with respect to recycle of electrophotographic photoconductors from the viewpoint of social needs i.e. resource saving and energy saving (see JP-A Nos. 09-211875, 2000-221704, 2003-98694, 08-6264, 11-095453 and 2005-221910).
In these proposals without exception, photosensitive layers are peeled away and raw aluminum pipes are re-coated with a photosensitive layer. However, there exist many sufficiently usable electrophotographic photoconductors among those collected from markets by virtue of recent improved quality of electrophotographic photoconductors; in such cases, it will be preferred from the viewpoint of resource and energy savings that the electrophotographic photoconductors are recycled without peeling the photosensitive layers.
JP-A No. 2005-266316 discloses that the percentage of usable organic photoconductor (OPC) drums is not lower among disposed or recycled OPC drums, provided that the thickness of photoconductor layers remains at a level of no less than one-fourth of the initial thickness even when some sort of degradation appears on certain properties; in particular, in cases where the OPC drums are utilized in digital image forming apparatuses such as laser printers and digital copiers, deterioration in electric properties in OPC drums is likely to be negligible since image-density change tends to be unnoticeable by virtue of image information from digital signals. It is also disclosed that OPC drums with abnormal image quality due to adhesion of foreign matters etc. can be reused after cleaning and removing the foreign matters.
As described above, in cases where electrophotographic photoconductors after use for image formation or electrophotographic photoconductors within process cartridges after use are to be reused, the electrophotographic photoconductors may be sufficiently usable provided that the photosensitive layers are less abraded and electrical property changes are slight.
However, all of these used electrophotographic photoconductors are not always reusable; for example, electrophotographic photoconductors having undergone troubles such as paper jams or filmings may be unusable in spite that the abrasion of photosensitive layers is little and the change of electrical properties is slight.
In addition, electrophotographic photoconductors having been used for image formation typically bear numerous fine flaws on the surfaces. These flaws often emerge and run in the circumferential direction; in cases where the flaws are shallow, the evaluation should be judged as pass since causing no problem on their reuse. On the other hand, filmings also often emerge in the circumferential direction like flaws, and the evaluation should be judged as rejection since such filmings typically influence the quality of images to non-negligible levels provided that the filmings exist slightly on the surfaces of electrophotographic photoconductors.
Accordingly, in cases where electrophotographic photoconductors are to be reused, examination and judgment are indispensable with respect to filming occurrence and reusability of the electrophotographic photoconductors. However, there exist fine flaws on the surfaces of electrophotographic photoconductors having been used for image formation, which making difficult to detect filmings efficiently.
As such, in order to determine the reusability of electrophotographic photoconductors within image forming apparatuses collected from markets, for example, various patterns of images may be formed using the image forming apparatuses collected from markets themselves. However, image forming apparatuses are typically utilized in various and inconsistent manner, thus the conditions thereof are often maintained improperly; for example, even when abnormal images generate for the collected image forming apparatuses with photoconductors as they are, the electrophotographic photoconductors may have no problem themselves.
Furthermore, in order to examine in such a manner, the electrophotographic photoconductors must be collected in their own image forming apparatuses therewith, which leading to a problem that those having larger volume and mass should be transported to sites for regenerating thereof.
In addition, outer packages of image forming apparatuses are typically of plastics, thus usually, iron materials are employed for their frames, and also printed wiring boards with electronics parts and laser sources etc. are mounted therein. In cases where these image forming apparatuses are collected from markets, they must be decomposed, and materials including plastics, iron, aluminum etc. must be distinguished at their regenerating sites. However, when image forming apparatuses are operated in a condition that electrophotographic photoconductors are mounted, there exists a problem that the decomposition and collection of each material must be carried out at the last stage.
In order to solve these problems, a method may be envisaged such that an image forming apparatus solely for the purpose of examination is provided, an electrophotographic photoconductor is mounted on the specific image forming apparatus for examination then examined through outputting images. However, this method takes a lot of troublesome task for the examination, since attachment and detachment to and from the specific image forming apparatus for examination are required for the respective examinations.
Moreover, process cartridges, in some cases, cannot be operated for example by reasons that (i) toner depletion from process cartridges, (ii) defects in cleaning blades, (iii) smear on charging rollers, (iv) filled waste toner tanks of cleaning units etc. although the electrophotographic photoconductors represent no significant problems such as abrasion, flaws, filmings etc. and are still usable themselves. These process cartridges in the cases of (i) to (iv) can be reused by way of removing the reasons to disturb their usage, such as operation to discard the waste toner from the waste toner tank, operation to exchange the cleaning blade, operation to refill the toner, operation to wipe the surface of the developing roll and operation to exchange the charging unit like a charging roll.
However, these process cartridges also require the evaluation as to the reusability of electrophotographic photoconductors since they cannot be used due to local flaws or filmings when such flaws or filmings are induced by troubles like paper Jam or filmings in use regardless of less abrasion in photosensitive layers.
As described above, the evaluation in terms of filming occurrence is essential in cases where electrophotographic photoconductors are reused; however, the determination as to the reusability is difficult since used electrophotographic photoconductors bear numerous fine flaws or streaks on the surfaces, therefore, the improvement or development are currently demanded still further with respect to the evaluation.